Hermetic Compressor

ABSTRACT

A hermetic compressor has a hermetic container, a suction pipe, a compressing mechanism and a suction muffler. The suction pipe includes a large diameter part opening to an inside of the hermetic container and a small diameter part connected to an external refrigerating system, and the suction pipe is fixed with the hermetic container. The compressing mechanism is accommodated inside the hermetic container. The suction muffler forms a muffling space communicated with the compressing mechanism. The suction muffler is provided with an inlet opening which communicates the muffling space with an inside space of the hermetic container and faces closely an opening of the large diameter part of the suction pipe.

TECHNICAL FIELD

This invention is related to a hermetic compressor to be used for arefrigerator and the like.

BACKGROUND ART

A hermetic compressor is disclosed in U.S. Pat. No. 5,496,156 forinstance, in which an inlet opening of a suction muffler is disposedclosely facing a suction pipe for achieving a high efficiency. Theconventional hermetic compressor is explained hereinafter with referenceto a drawing.

FIG. 4 is a cross-sectional view of the conventional hermeticcompressor. Suction pipe 2 which opens into hermetic container 1 isfixed with hermetic container 1. Hermetic container 1 containscompressing mechanism 7 which includes cylinder 4 in which piston 3reciprocates, and suction muffler 6 forming muffling space 5. Suctionmuffler 6 is provided with inlet opening 8 communicating muffling space5 with a space of inside hermetic container 11. Inlet opening 8 isdisposed closely facing suction pipe 2.

A motion of thus constituted hermetic compressor is explained next.Piston 3 reciprocates inside cylinder 4, thereby cooling medium flowingfrom an external refrigerating system (not illustrated) through suctionpipe 2 is once released into hermetic container 1. The cooling medium isdrawn into suction muffler 6 through inlet opening 8, and thenintermittently drawn into cylinder 4 through muffling space 5. At thistime, since suction pipe 2 and inlet opening 8 are closely faced eachother, the cooling medium is drawn into suction muffler 6 with keepingits relatively low temperature. Consequently, drawn mass of the coolingmedium (cooling medium circulating amount) per unit period of timebecomes large therefore efficiency is increased, thus efficiency of thehermetic compressor is enhanced.

However, with above-mentioned constitution, when the cooling medium isreleased through suction pipe 2 into hermetic container 1, the coolingmedium is mixed with high temperature cooling medium that already existsin the hermetic container 1. Thereby, the temperature of the coolingmedium introduced by inlet opening 8 into cylinder 4 becomes higher thanthe cooling medium at an opening portion of suction pipe 2. Because ofthe reason, cooling medium circulating amount is reduced, insufficientlyenhancing efficiency of the compressor.

SUMMARY OF THE INVENTION

A hermetic compressor of the present invention has a hermetic container,a suction pipe, a compressing mechanism and a suction muffler. Thesuction pipe includes a large diameter part which opens into an insideof the hermetic container and a small diameter part connected to anexternal refrigerating system. The suction pipe is fixed with thehermetic container. The compressing mechanism is accommodated inside thehermetic container. The suction muffler forms a muffling space which iscommunicated with the compressing mechanism. The suction muffler isprovided with an inlet opening which communicates the muffling spacewith an inside space of the hermetic container and faces closely anopening of the large diameter part of the suction pipe. With thisconstitution, low temperature cooling medium can be introduced to thecompressing mechanism, so that a hermetic compressor having a highrefrigerating efficiency is obtained.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross-sectional view of a hermetic compressor in accordancewith an exemplary embodiment of the present invention.

FIG. 2 is an expanded view of a main part of FIG. 1.

FIG. 3 is a graphical illustration showing a relation between arefrigerating performance and volume of a large diameter part of thehermetic compressor in accordance with the exemplary embodiment.

FIG. 4 is a cross-sectional view of a conventional hermetic compressor.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENT

Hereinafter, an exemplary embodiment of the present invention isdescribed with reference to drawings. The description of the embodimentdoes not necessarily limit the invention.

FIG. 1 is a cross-sectional view of a hermetic compressor in accordancewith the exemplary embodiment of the present invention, and FIG. 2 is anexpanded view of a main part of FIG. 1.

Hermetic container 104 contains motor 108 having stator 106 and rotor107, and compressing mechanism 109 driven by motor 108. Motor 108 andcompressing mechanism 109 are flexibly-supported by spring 110 placedinside hermetic container 104. Hermetic container 104 is filled withcooling medium.

Compress mechanism 109 includes shaft 111 fixed with rotor 107, cylinder114, piston 112 reciprocating inside cylinder 114, and connecting rod113 connecting shaft 111 with piston 112. Suction muffler 116 formsmuffling space 115 that is communicated with cylinder 114. Inlet opening117 communicates muffling space 115 with a space inside hermeticcontainer 104. Inlet opening 117 is formed on outer surface 118 ofsuction muffler 116 so that inlet opening 117 closely faces opening 105of suction pipe 101. As shown in FIG. 2, inlet opening 117 is preferablyopened and protruded a little from outer surface 118.

Suction pipe 101 has large diameter part 102 and small diameter part103. Large diameter part 102 is fixed with hermetic container 104 and isopened to hermetic container 104 at opening 105. Small diameter part 103is connected to a lower pressure side of an external refrigeratingsystem (not illustrated). Internal diameter D1 at opening 105 ispreferably larger than opening diameter D2 of inlet opening 117, andlength L1 of large diameter part 102 is preferably longer than internaldiameter D1 of large diameter part 102. Length L1 stands for a distancefrom opening 105 to small diameter part 103.

Volume V1 defined by large diameter part 102 is preferably about 0.5times as large of effective cylinder volume V2 of compressing mechanism109. Effective cylinder volume V2 stands for volume of cylinder 114measured from a bottom dead center to a top dead center of piston 112.Distance L2 between inlet opening 117 and opening 105 is preferablyabout 0.7 times as large of opening diameter D2 of inlet opening 117.

Motion and working of thus constituted compressor is explained next.When rotor 107 of motor 108 rotates, piston 112 reciprocates in cylinder114. In a suction process where piston 112 moves from the top deadcenter to the bottom dead center, pressure inside cylinder 114 isdecreased, drawing cooling medium existing in muffling space 115 ofsuction muffler 116 into cylinder 114. Pressure inside muffling space115 is thus decreased and draws in cooling medium that exists inhermetic container 104 through inlet opening 117. At that time, thecooling medium flows into hermetic container 104 from the externalrefrigerating system (not illustrated) through suction pipe 101.

In a following compressing process where piston 112 moves from thebottom dead center to the top dead center, piston 112 compresses coolingmedium in cylinder 114. The compressed cooling medium is discharged tothe external refrigerating system.

As described above, compressing mechanism 109 repeats suction processand discharge process as piston 112 makes the reciprocating movement. Inthese processes, the cooling medium inside muffling space 115 isintermittently drawn into cylinder 114, and the cooling medium inhermetic container 104 is intermittently drawn into the mechanismthrough inlet opening 117.

Volume in hermetic container 104 is significantly larger than effectivecylinder volume V2 of compressing mechanism 109, thereby intermittentdrawing action of cooling medium through inlet opening 117 is smoothed.Therewith, the cooling medium flows into hermetic container 104 almostcontinuously from the external refrigerating system through suction pipe101.

The cooling medium returned from the external refrigerating system isusually in a temperature which is close to outside air temperature,namely the cooling medium arriving in large diameter part 102 of suctionpipe 101 retains this low temperature level. On the other hand,temperature of the cooling medium in hermetic container 104 is raisedfar higher than the outside air temperature as the cooling medium isexposed to high temperature compressing mechanism 109 and motor 108.

In this exemplary embodiment, inlet opening 117 is disposed closelyfacing opening 105 of suction pipe 101, letting the low temperaturecooling medium in large diameter part 102 drawn in intermittentlythrough inlet opening 117. Namely, the low temperature cooling medium issupplied to cylinder 114. Consequently, a refrigerating capacity of thecompressor is increased therefore refrigerating efficiency of thecompressor is enhanced.

If inlet opening 117 of suction muffler 116 and outer surface 118 aredisposed forming an obtuse angle, or if an inner periphery of inletopening 117 is largely chamfered in a shape of a bugle, therefrigerating capacity is not greatly increased. This is because thecooling medium heated to a high temperature at around inlet opening 117is drawn in by a higher percentage.

In this exemplary embodiment, inlet opening 117 is slightly protrudedfrom outer surface 118 of suction muffler 116. With this structure,inlet opening 117 can selectively draw in cooling medium that exists inlarge diameter part 102 toward which inlet opening 117 is extended. Itis interpreted that this is because a suction path of less disturbedcooling medium gas is formed around the extended line of inlet opening117. Alternately, having inlet opening 117 protruded, inlet opening 117of suction muffler 116 and outer surface 118 of suction muffler 116 canbe disposed forming an acute angle. With this arrangement, therefrigerating capacity of the compressor is also increased, enhancingrefrigerating efficiency of the compressor. Even if the angle made byinlet opening 117 and outer surface 118 of suction muffler 116 areslightly dull, or even if inlet opening 117 has a curved finish or ischamfered, inlet opening 117 can selectively draw in the cooling mediumexisting in front of inlet opening 117.

In this exemplary embodiment, volume V1 in large diameter part 102 ofsuction pipe 101 is made about 0.5 times as large of effective cylindervolume V2 of compressing mechanism 109. Most of the low temperaturecooling medium stored in large diameter part 102 is drawn inintermittently through inlet opening 117 and then inside of largediameter part 102 is momentarily replaced by high temperature coolingmedium existing in hermetic container 104. However, by takingabove-mentioned ratio in volumes, the cooling medium is almostcontinually flowed from the external refrigerating system to suctionpipe 101, namely inside large diameter part 102 of suction pipe 101 isrefilled with the cooling medium having a temperature close to outsideair temperature. With this process repeated, the low temperature coolingmedium is continually supplied to suction muffler 116, greatlyincreasing the refrigerating capacity, consequently making therefrigerating efficiency of the compressor significantly high.

Motor 108 and compressing mechanism 109 are flexibly-supported by spring110. This arrangement may occasionally cause mismatching of the extendedline of inlet opening 117 with opening 105, of suction pipe 101.However, in this exemplary embodiment, internal diameter D1 of opening105 is made larger than opening diameter D2 of inlet opening 117.Namely, the opening area of opening 105 is larger than that of inletopening 117. Thus, the extended line of inlet opening 117 does notgreatly deviate from a scope of internal diameter D1 of opening 105,even when compressing mechanism 109 moves a little. Thereby, variationin efficiency of the compressor is kept small.

In this exemplary embodiment, length L1 of large diameter part 102 ismade larger than internal diameter D1 of large diameter part 102. Withthis arrangement, the cooling medium stream flowed from small diameterpart 103 to large diameter part 102 is stabilized. If the length oflarge diameter part 102 is short, the cooling medium stream flowed fromsmall diameter part 103 to large diameter part 102 is disturbed due to achange of the diameters. The cooling medium arriving at opening 105 withits stream disturbed flows into hermetic container 104 diffusely. Bymaking length L1 of large diameter part 102 long as in this exemplaryembodiment, the cooling medium stream is stabilized. Accordingly, thecooling medium flowing into hermetic container 104 is steamed towardinlet opening 117 that closely faces large diameter part 102.

Suction pipe 101 is fixed with hermetic container 104 which is in hightemperature, so the cooling medium becomes hot receiving heat fromhermetic container 104. Naturally, the cooling medium stored in V1,inside volume of large diameter part 102, is heated easily in a vicinityof opening 105. If length L1 of large diameter part 102 gets longer, apercentage of the cooling medium that becomes hot in the staying coolingmedium is reduced, consequently supplying low temperature cooling mediumto suction muffler 116. With these effects, lower temperature coolingmedium is supplied to cylinder 114, enhancing the refrigeratingefficiency of the compressor.

Next, details of dimensional specification are described with theirparameterized numbers. FIG. 3 shows the measured efficiency of thehermetic compressor using parametric ratio between volume V1 of largediameter part 102 and effective cylinder volume V2 of compressingmechanism 109. Apparently shown in FIG. 3, refrigerating performance isgreatly increased when the ratio is 0.1 or larger. As the ratioincreases, the efficiency is also increased. When volume V1 is too smallcompared to effective cylinder volume V2, an amount of low temperaturecooling medium stored in large diameter part 102 is not enough for thatdrawn in through inlet opening 117 of suction muffler 116. So, a largeamount of high temperature cooling medium existing in hermetic container104 is drawn together in. Because of this phenomenon, it is consideredthat refrigerating performance is enhanced when the ratio is 0.1 orhigher.

When the ratio of volume V1 to effective cylinder volume V2 exceeds 0.6,increase of refrigerating performance is saturated. It is consideredbecause the cooling medium stored in volume V1 of large diameter part102 reaches an amount sufficient enough for the amount drawn throughinlet opening 117.

When volume V1 of large diameter part 102 is unnecessarily large,problems arise. For example, cost increases, size of the compressorbecomes large, and installation of the compressor is restricted. Toavoid such problems, the ratio of volume V1 formed in large diameterpart 102 to effective cylinder volume V2 formed in compressing mechanism109 is suitably defined to be at least 0.1 and at most 0.6.

Finally, preferable distance L2 between inlet opening 117 and opening105 is explained. If inlet opening 117 is situated too far from opening105, inlet opening 117 easily draws in high temperature cooling mediumexisting in hermetic container 104, reducing a refrigeratingperformance. If it is too closely situated, inlet opening 117 may touchhermetic container 104 or suction pipe 101 when compressing mechanism109 is moved, for example, during transport. At that time suctionmuffler 116 may damaged. To avoid of such incident, a ratio of distanceL2 between inlet opening 117 and opening 105 to opening diameter D2 ofinlet opening 117 is preferably defined at least 0.3 and at most 1.0.With this arrangement, high reliability is obtained while maintaininghigh efficiency.

INDUSTRIAL APPLICABILITY

A hermetic compressor according to the present invention has highefficiency. Therefore, it can be applied to a refrigerator, anair-conditioner, a refrigerating freezer, and so on.

1. A hermetic compressor comprising: a hermetic container, a suctionpipe including a large diameter part having an opening and a smalldiameter part connected to an external refrigerating system, the suctionpipe being fixed with the hermetic container, and the large diameterpart opening to an inside of the hermetic container, a compressingmechanism being accommodated inside the hermetic container, and asuction muffler for forming a muffling space communicated with thecompressing mechanism, the suction muffler being provided with an inletopening, the inlet opening communicating the muffling space with aninside space of the hermetic container and closely facing the opening ofthe large diameter part of the suction pipe.
 2. The hermetic compressoraccording to claim 1, wherein an opening area of the large diameter partis larger than an opening area of the inlet opening.
 3. The hermeticcompressor according to claim 1, wherein the inlet opening is protrudedfrom an outer surface of the suction muffler.
 4. The hermetic compressoraccording to claim 1, wherein a distance from the opening of the largediameter part to the small diameter part is larger than an internaldiameter of the large diameter part.
 5. The hermetic compressoraccording to claim 1, wherein the compressing mechanism includes acylinder and a piston reciprocating inside the cylinder.
 6. The hermeticcompressor according to claim 5, wherein volume of the large diameterpart is at least 0.1 times and at most 0.6 times of volume in thecylinder from a bottom dead center of the piston to a top dead center ofthe piston.
 7. The hermetic compressor according to claim 1, wherein adistance between the inlet opening and the opening of the large diameterpart is at least 0.3 times and at most 1.0 times of a diameter of theinlet opening.